Samsung NX20 Optics

18-55mm Zoom
A typical zoom ratio for a kit lens, with good performance.

The Samsung NX20 is available bundled with the Samsung 18-55mm f/3.5-5.6 OIS NX lens, which has a 35mm equivalent focal range of about 27-84mm. Its 3.1x zoom ratio is about average for a kit lens. Optical performance is quite good at 18mm, with very good sharpness and contrast across most of the frame at f/8, and just minor softness in the corners. Coma distortion in the trees is low, and chromatic aberration very well controlled (suppressed by the camera), though some minor flare can be seen around bright highlights. Results are also very good at 33mm, with very good sharpness across the frame and negligible chromatic aberration. At full telephoto, sharpness and contrast are quite good in the center, but corners and edges are a little soft, particularly on the right side. Chromatic aberration is still very low, though. Overall, far-field performance is pretty good for a kit lens, and the optical image stabilization built-in to the lens will come in handy for low-light shots.

Macro
A larger-than-average minimum coverage area, with good detail in the center. Flash was partially blocked, and somewhat dim.

As with zoom performance, the Samsung NX20's macro performance will depend entirely on the lens in use. However with the 18-55mm kit lens set to 55mm, the Samsung NX20 captured a larger-than-average minimum area measuring 3.57 x 2.38 inches (91 x 61 millimeters). Sharpness is pretty good in the center of the frame, just a touch soft, but corners are quite a bit softer. (Most lenses show some softening in the corners at macro distances.) The flash was partially blocked by the lens at closest focus, and throttled-down a bit too much, making a dim, uneven exposure.

Geometric Distortion
High distortion at both wide-angle and telephoto with Distortion Correction disabled, though low distortion at wide-angle when enabled.

With Distortion Correction enabled by default, the 18-55mm kit lens' barrel distortion at wide-angle was overcorrected slightly to about 0.1% pincushion. At full telephoto, distortion is a little high and noticeable at 0.7% pincushion, where Distortion Correction didn't make a difference. It's worth noting here that the default seems to have changed from the prior generation of Samsung CSCs, with distortion correction on by default instead of off. We also don't see part of the framed image cropped away by Distortion Correction like we did with the NX200, which is a nice improvement. This is the tendency for the lens to bend straight lines outward (like a barrel -- usually at wide-angle) or inward (like a pincushion -- usually at telephoto).

With Distortion Control disabled, the Samsung NX20's 18-55mm kit lens produced higher-than-average distortion at both wide-angle and telephoto ends. At wide-angle, barrel distortion is 0.9% and at telephoto, pincushion distortion is unchanged at about 0.7%.

Chromatic Aberration and Corner Sharpness
JPEGs have low to moderately low chromatic aberration, though uncorrected raw files have much higher. The lens produced some soft corners at both wide-angle and telephoto.

Chromatic Aberration. Chromatic aberration in the corners with the NX20's 18-55mm kit lens at wide-angle (18mm) is moderate in terms of the number of pixels, but not very bright, so it's only slightly noticeable in some shots. At full telephoto (55mm), chromatic aberration is fainter and less noticeable. 

Corner Softness. The lens produced some soft corners in a few shots, though performance wide-open is better than average for a kit lens. At maximum wide-angle, all four corners exhibit minor blurring and loss of contrast, and softness does extend fairly deep into the frame. The center of the image is however very sharp with excellent contrast. At full telephoto, the bottom right corner is soft with lower contrast, however the other corners are sharper. The center is fairly sharp with good contrast, just a touch softer than wide-angle.

Vignetting. There's a bit of corner shading ("vignetting") at both wide-angle and telephoto when wide-open as indicated by the darker corner crops, but light fall-off isn't really an issue with this lens.

Stopped down to f/8, corners improve at both wide-angle and telephoto, but still remain slightly soft. Vignetting is negligible at both wide-angle and telephoto.

C.A. Reduction in JPEGs. As you can see from the crops above comparing in-camera JPEGs (left) to Adobe Camera Raw converted SRW files (right) taken with the 18-55mm lens, the Samsung NX20's image processor does a good job at suppressing much of the lateral chromatic aberration produced by the lens during its processing of JPEG files.

Accuracy
Excellent accuracy from the EVF and AMOLED monitor.

The Samsung NX20's electronic viewfinder and AMOLED monitor proved to be quite accurate, both showing just under 100% coverage with the 18-55mm kit lens at wide-angle and full telephoto. Excellent results here, especially considering the amount of distortion correction applied at wide-angle.